Influence Of Internal Heat Source Research Articles

Dufour and Soret effects on double diffusive Casson fluid flow with the influence of internal heat source

AbstractThis study focuses on the control of the cross-diffusion effects on the thermosolutal Casson fluid stream with an internal heat source. These effects have practical applications in geothermal energy extraction, cooling of electronic devices, petroleum engineering, and polymer processing. With the help of similarity transformations, the governing equations are transformed to nonlinear ordinary differential equations (ODEs). The highly nonlinear differential equations are solved with the help of Bernoulli wavelet numerical scheme, and the outputs are compared with previous literature to validate the findings. The study investigates the forces of various physical parameters on the velocity, temperature, and concentration of the fluid and presents the outcomes in graphical form. In addition, the study provides information on skin friction, heat and mass transfers in tabular format. Overall, the research contributes to a better understanding of the behaviour of non-Newtonian fluids under different thermal and concentration gradients and has practical implications in various industrial processes. Our findings demonstrate the remarkable effectiveness and accessibility of the Bernoulli wavelet method in solving coupled nonlinear ODEs of this nature. The results exhibit outstanding agreement, particularly in engineering applications involving coupled nonlinear ODEs.

Numerical simulation study on the effect of internal heat source on pumping ventilation

Natural ventilation is a passive building technology that can reduce energy consumption for mechanical cooling of the indoor environment. Natural ventilation technology has received renewed attention from researchers. Theoretical studies on natural ventilation have evolved from a steady state to a non-steady state. Pumping ventilation is distinct from other ways of natural ventilation in that its flow direction alternatingly changes from the indoor to the outdoor. However, all published studies did not consider the influence of internal heat sources in pumping ventilation, and there are few discussions about the fluid periodic variation in wind-thermal coupling studies. Based on a previous study, the numerical simulation of single-sided pumping ventilation with two openings in the same wall driven by wind and thermal pressure is conducted in the paper. The influence of heat source intensity and the height of the location of the heat source are analyzed. The applicability of different ventilation rate calculation formulas is discussed. The results show that the indoor airflow oscillation frequency decreases in the effect of wind and thermal pressure, compared to driven by air pressure alone. However, changing the height location and intensity of the heat source does not affect the frequency characteristics in these cases.

Darcy–Benard–Oldroyd convection in anisotropic porous layer subject to internal heat generation

An anisotropic horizontal porous layer saturated with viscoelastic liquids of the Oldroyd-B type is explored to determine how the internal heat source affects thermal convection. As a momentum equation, a modified Darcy–Oldroyd model is used that takes into account the anisotropy of the porous layer. The energy equation is formulated in such a way that the influence of internal heat sources and anisotropy in thermal diffusivity on the stability criterion may be easily identified. The effects of anisotropy, viscoelasticity, and internal heat generation on the onset of thermal convection are investigated using linear stability analysis. It is understood that convection begins via an oscillatory mode instead of a stationary mode because viscous relaxation, thermal diffusions, and internal heat generation mechanisms compete with one another. Both steady and unsteady finite-amplitude convections are studied using nonlinear stability analysis with the truncated Fourier series method. The effect of different governing parameters on the system’s stability and on convective heat transfer is studied. The present investigation has been significantly validated by the recovery of several prior results as special situations. The findings presented in this work are anticipated to have significant implications for a number of real-world applications, including modeling of oil reservoirs, crude oil extraction, crystal growth, the pharmaceutical and medical industries, and the use of geothermal energy, among others.

INSTABILITY INVESTIGATION OF THERMO-BIOCONVECTION OF OXYTACTIC MICROORGANISM IN JEFFREY NANOLIQUID WITH EFFECTS OF INTERNAL HEAT SOURCE

The intent of this article is to investigate the influence of internal heat source on the stability of a suspension containing oxytactic microorganisms in a shallow horizontal porous fluid layer saturated by Jeffrey nanoliquid. The Jeffrey-Buongiorno model governs the nanofluid bioconvection flow. Normal mode analysis is utilized, and the principle of exchange of stability is invoked due to the absence of opposing agencies. The stability criteria is defined in terms of critical thermal Rayleigh number as a function of various flow governing parameters by using the weighted residual Galerkin method. It is perceived that the increment of uniform heat supply and the presence of oxytactic microorganism cells as well as the nanoparticles enhances heat transfer and constitutes an unstable system that hastens bioconvection. The nanoparticle Lewis number is found to have a dual impact on the system stability that relies on the nanoparticle Rayleigh number and exhibits destabilizing nature for top-heavy nanoparticle concentration. It is also observed that the Jeffrey parameter produces nonoscillatory instability in the system.

Construction of dynamic temperature field model of ball screw based on superposition of positive and negative temperature fields

In order to study the influence of internal heat source of ball screw feed transmission system on the thermal error of ball screw, the theoretical modeling and experimental research are carried out on the temperature field and temperature rise characteristics of ball screw in this paper. Firstly, on the basis of analyzing heat generation mechanism and heat transfer of ball screw, the positive temperature field of ideal heat transfer of heat source and the negative temperature field caused by heat transfer are derived. In addition, the mathematical model of dynamic temperature field of ball screw feed system about time and position is established according to the superposition principle of temperature field, and the temperature field and thermal error of x-axis ball screw in horizontal machining center are measured. Secondly based on the experimental temperature field data, a complete finite element model of the temperature field of the ball screw feeding system is constructed, and temperature at any point of the system and the undetermined coefficient of the numerical model of temperature field under this working condition are determined by the finite element model. Finally, the thermal error distribution of the ball screw is calculated by the numerical model, the theoretical and experimental error distributions are compared, and the correctness of the theoretical model of the temperature field under this working condition is verified.

Generalized stokes’ flow and radiative heat transfer model of a non-Newtonian fluid in a darcy porous medium subject to Navier’s slip conditions on the penetrable porous boundary: Group theoretical and compatibility analysis

In this work, the generalized Stokes’ model of a non-Newtonian fluid is discussed. The incompressible time-dependent flow and radiative heat transfer model of a non-Newtonian third grade fluid over a moving porous boundary is considered. The fluid flows into the porous region in the half space geometry. The flux disturbance caused by the impulsive movement of the porous boundary is studied. The energy equation is studied under the influence of internal heat source and thermal radiation. The flow and heat transfer model meets the Navier’s slip conditions at the boundary which allows the extremes of no-slipping at the penetrable surface. Lie symmetry analysis is carried out to calculate the complete Lie symmetry algebra associated with the modelled nonlinear partial differential equations. Symmetry operators are used to find self-similar transformations which help to perform reduction of the governing nonlinear partial differential equations to different classes of nonlinear ordinary differential equations. Reduced ordinary differential equations, as a result of the implication of symmetry reductions, are solved by employing the general compatibility approach. Furthermore, we have discussed the non-classical symmetry algebra, associated with the model, to classify all possible closed-form exact solutions of the flow model. The effect of various pertinent parameters on the flow and heat transfer model is studied in detail.

Influence of Heat Source on Thermal Behaviour of Solid Cylinder.

The present manuscript deals with determination of influence of internal heat source on thermal behaviour of a long solid cylinder. A direct, steady state, nonhomogeneous boundary value problem with internal heat generation is formulated to analyse heat transfer and thermal stresses. The cylindrical surface heat source situated in annular region of long cylinder results in internal heat generation. Finite Hankel transform, Goodier’s thermoelastic displacement potential and Michell function are adopted to obtain the analytical solution. The outcomes are represented in the form of infinite series comprising Bessel’s functions. By considering a mathematical model for steel plate, outcomes are verified numerically. Some numerical results for the temperature distribution, displacement components, and the associated stresses are shown in figures drawn using Matlab software.

Study into the Influence of Internal Heat Sources on the Operating Characteristics of a Thermoelectric Generator

The influence of internal heat sources on temperature distribution during the operation of thermoelectric generators (TEG) is investigated. Taking into account various factors affecting the temperature regime, including internal heat sources, a multilevel model of a two-stream TEG has been developed, which allows one to calculate the temperature distribution and the integral characteristics of the generator. The calculations were carried out using the PHOENICS program package; as a result, the dependences of the electrical characteristics and the temperature drop on the junctions on the load resistance, speed, and coolant temperature were obtained. A comparison is made with the corresponding indicators in the absence of internal heat sources. It is concluded that the influence of internal heat sources on the temperature drop and electric power increases with decreasing load resistance. Thus, in the maximum power mode, which corresponds to the ratio of the load resistance to the internal resistance of the module m = 1.15, the temperature drop decreases by 3.5–4.0%, while that at m = 0.01 is by 7.5–8.5%. TEG power in maximum power mode decreases by 7.5–8.0%. Studies have shown that the influence of internal heat sources on the characteristics of the TEG is more substantial when the flow rate in the heat exchangers is lower. The greatest decrease in the values of indicators due to the influence of internal sources was observed at v = 0.2 m/s and amounted in maximum power mode to 5.5–6.0% for the temperature difference and 12–13% for power. The results obtained indicate that the influence of internal sources on the characteristics of TEGs is significant enough, which implies that the most accurate estimates of the thermal and electrical performance of TEGs can be made only by taking into account the effect of internal heat sources on the temperature distribution in TEGs.

Thermal Sources of Errors in Surface Texture Imaging

This paper presents the influence of thermal phenomena on areal measurements of surface topography using contact profilometers. The research concerned measurements under controlled and variable environmental conditions. The influence of internal heat sources from profilometer drives and their electronic components was analyzed. For this purpose, a thermal chamber was designed and built. Its task was to maintain and control environmental conditions and, at the same time, separate the profilometer from external disturbances. Heat sources and temperature values for elements and systems were determined. It further enabled for the calculation of the displacements in axes as a function of temperature. The largest displacement in the probe due to internal heat sources for the considered cases occurred in the X-axis direction. Its value reached 16.2 μm. However, the displacement in the probe in the Z-axis direction had the greatest impact on the measured surface topography. These displacements for a thermally unstable profilometer reached 7.9 μm in Z, causing results even 90% greater than in the case of a device without such problems. The time after which a proper topography measurement can be started was also determined basing on obtained data. This time for tested profilometers was between 6 and 12 h. It was found that performing thermal stabilization of the profilometer significantly reduced surface irregularity errors. The stabilization time should be determined individually for a specific type of device.

Bivariate spectral quasi-linearisation exploration of heat transfer in the boundary layer flow of micropolar fluid with strongly concentrated particles over a surface at absolute zero due to impulsive

The problem of unsteady micropolar fluid flow over a surface in which the heat energy falls at a lower limit of thermodynamic temperature scale due to impulsive is investigated. In this article, a new spectral method (BSQLM) for solving the partial differential equation is shown to unravel the heat transfer within the boundary layer. Some fluid layers at the free stream were given an impulsive motion in the horizontal direction. The thermal conductivity of the non-Newtonian fluid is assumed to be temperature dependent due to the influence of internal heat source; hence modified to suit the case of melting heat transfer following all the fundamental theories. The mathematical model was non-dimensionalised and parameterised using similarity transformation suitable to unravel the flow at short-time and long-time periods. Smooth transitions within the time frame 0 ≤ ξ ≤ 1 in the domain 0 ≤ η ≤ 1 are observed. The minimum temperature distribution is ascertained when the magnitude of Prandtl number is significantly large.

Influence of internal heat sources on thermal resistance evaluation through the heat flow meter method

Buildings energy performance is evaluated using codes which reproduce the building behavior, employing technical information about the structure. Wall thermal resistance can be measured using a heat-flow meter in compliance with the ISO 9869, which suggests avoiding proximity to particular points such as thermal bridges, but it does not give suggestions about how to deal with internal heat sources. Thermal resistance measurements are based on 1D models and the internal heat sources cause the departure from one-dimensional conditions. In this study we employ a FEM code to reproduce the heat-flow meter method within a 2D model. Walls include an internal pipe, inside which hot/cold water flows. Models were generated considering different stratigraphies and heat-flow plate positions along the inner side of the wall, in order to reproduce the thermal conditions that affect the flowmeter and the wall, respectively. Thus, it is possible to compare the thermal resistances of the different walls and to find the best heat-flow plate positions in order to minimize the influence of the internal heat source. A preliminary experimental evidence of the problem has been finally presented and the results of this case study have been compared with those of its corresponding FEM model.

Melting heat and mass transfer in stagnation point micropolar fluid flow of temperature dependent fluid viscosity and thermal conductivity at constant vortex viscosity

Abstract Steady mixed convection micropolar fluid flow towards stagnation point formed on horizontal linearly stretchable melting surface is studied. The vortex viscosity of micropolar fluid along a melting surface is proposed as a constant function of temperature while dynamic viscosity and thermal conductivity are temperature dependent due to the influence of internal heat source on the fluid. Similarity transformations were used to convert the governing equation into non-linear ODE and solved numerically. A parametric study is conducted. An analysis of the results obtained shows that the flow-field is influenced appreciably by heat source, melting, velocity ratio, variable viscosity and thermal conductivity.

Numerical study of the influence of internal heat source in naturally ventilated offices

The natural ventilation in a building performs a fundamental role in users' welfare and health, when used as a bioclimatic and architectural strategy, it can provide brighter projects. Increasing the indoor air speed ventilation has an important performance maintaining indoor air quality, contributing to thermal interactions between human body and environment, which can significantly reduce the building's energy cost. In this study, a numerical research of natural convection in single-sided and cross ventilation is developed using the finite volume method, taking account the internal heat sources influence. The numerical model is used to determine the effects of wind and thermal forces combined by analyzing the stream functions and temperature distribution within an office. The turbulence model is the two differential equations for the low Reynolds number. The building's internal heat sources influence is analyzed herein. The results show that the single-sided ventilation presents excellent conformity with the results obtained in literature. The influence of the internal heat source is considered and it has been observed that the best source position is near to the air exit for both single-sided ventilation and cross ventilation.

Steady-state thermal heat conductivity in rotor of ball asynchronous motor

The problem of how to develop a mathematical model of the heat processes that take place in the rotor of a spherical asynchronous motor under the influence of internal heat sources is considered. An analytic model of the process is suggested that makes it possible to solve the problems of determination of the extreme thermal modes of a motor and is well suitable for the searching procedures of the construction optimization problems.

Convection with internal heat sources and thermal turbulence in the Earth's mantle

SUMMARY The influence of internal heat sources on mantle convection is investigated using numerical calculations of 2-D thermal convection in an infinite Prandtl number, incompressible fluid. The geometry is a cylindrical annulus with inner and outer radii in proportion to the whole mantle. Time-dependent calculations are made starting from random initial conditions, with Rayleigh numbers RaT (based on boundary-temperature difference) and Ra, (based on internal-heat production) in the range 1dsRaTs lo7 and OsRa,524RaT. At fixed RaT, increasing Ra, results in transitions in flow structure from steady cells, to a pattern of stationary cells with time-variable amplitude, and finally to thermally turbulent convection with a non-stationary cell count. For RaT 10' and Ra, >RaT approximately, the travelling plumes disrupt the large-scale circulation, producing turbulent convection. At Ra, = lo7 the flow is fully developed thermal turbulence, and for Ra, > 0, consists of a rapidly fluctuating, irregular flow driven by transient rising and sinking sheets of buoyant fluid. Large fluctuations in total kinetic energy occur in this regime, with periodicities ranging from 40 to 1400Myr. The transition to thermal turbulence occurs in these calculations at Rayleigh numbers well below the value estimated for subsolidus convection in the mantle, suggesting thermally turbulent convection may occur in the mantle, a consequence of internal heat sources. Thermal turbulence offers an explanation for long-term fluctuations in the rate of subduction, sea-floor spreading and global volcanic activity.

Development of thermocapillary convection in a fluid cylinder and cylindrical and plane layers under the influence of internal heat sources

Development of thermocapillary convection in a fluid cylinder and cylindrical and plane layers under the influence of internal heat sources

Influence of internal heat sources on nonstationary heat transfer in disperse systems

The influence of internal heat sources on the effective thermophysical properties of disperse media is examined and relaxation equations are obtained. It is shown that the heat-conduction equation can be both hyperbolic and elliptic in type.